// 202102104046耿子杭
package cn.edu.sdjzu.xg.kcsj.util;

public class Pagination {
    // 返回LIMIT子句
    public String toLimitClause(int totalNum){
        // 向前台提供元组总数（totalNum为0不是错误）
        this.totalNum = totalNum;
        // 偏移量
        int offset = (this.pageNo - 1) * this.pageSize;
        // 输出LIMIT子句，注意关键字两端的空格
        return " LIMIT " + offset + ", " + this.pageSize;
    }

    public int getTotalPages(Pagination pagination){
        int totalPages = (int)((pagination.getTotalNum() - 1) / pagination.getPageSize() + 1);
        return totalPages;
    }

    public Pagination(int pageSize, int pageNo) {
        // 防止错误赋值
        if(pageNo > 0) {
            this.pageNo = pageNo;
        }else{
            this.pageNo = 5;
        }

        if(pageSize > 0) {
            this.pageSize = pageSize;
        }else {
            this.pageSize = 1;
        }

    }
    // 如果没有get方法，fastjson将无法读取对象属性
    public int getPageSize() {
        return pageSize;
    }

    public int getPageNo() {
        return pageNo;
    }

    public int getTotalNum() {
        return totalNum;
    }

    // 每页的对象(元组)数
    private int pageSize = 10000;
    // 页号
    private int pageNo = 1;
    // 对象(元组)总数
    private int totalNum = 1;

    @Override
    public String toString() {
        return "Pagination{" +
                "pageSize=" + pageSize +
                ", pageNo=" + pageNo +
                ", totalNum=" + totalNum +
                '}';
    }
}
